/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.graph;

/**
 * These bitmasks are used by edge-flipping algorithms to mark the edge order
 * relative to the original edge direction.
 */
public enum EdgeOrder {

	// bitmasks from triadic census
	FORWARD(0b10),
	REVERSE(0b01),
	MUTUAL(0b11);

	private final byte bitmask;

	EdgeOrder(int bitmask) {
		this.bitmask = (byte) bitmask;
	}

	/**
	 * Returns a bitmask used for marking whether an edge is in the same
	 * direction as in the original edge set (FORWARD), is flipped relative
	 * to the original edge set (REVERSE), or both (MUTUAL).
	 *
	 * @return edge order bitmask
	 */
	public byte getBitmask() {
		return bitmask;
	}
}
